[Bug go/65180] regression in gccgo testcase runtime/pprof on ppc64le, ppc64 following move to go 1.4 from 1.3

[boger at us dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65180

--- Comment #2 from boger at us dot ibm.com ---
We've been putting most of the discussion on this in the bugzilla mentioned in
the previous comment.

However there is a simple fix for Power which I will add here:

ndex: libgo/runtime/go-callers.c
===================================================================
--- libgo/runtime/go-callers.c  (revision 222128)
+++ libgo/runtime/go-callers.c  (working copy)
@@ -83,8 +83,20 @@ callback (void *data, uintptr_t pc, const char *fi
     }

   loc = &arg->locbuf[arg->index];
-  loc->pc = pc;

+  /* On the call to backtrace_full the pc value was most likely decremented
+     if there was a normal call, since the pc referred to the instruction
+     where the call returned and not the call itself.  This was done so that
+     the line number referred to the call instruction.  To make sure
+     the actual pc from the call stack is used, it is incremented here.
+
+     In the case of a signal, the pc was not decremented by backtrace_full but
+     still incremented here.  That doesn't really hurt anything since the line
+     number is right and the pc refers to the same instruction.
+  */
+
+  loc->pc = pc+1;
+
   /* The libbacktrace library says that these strings might disappear,
      but with the current implementation they won't.  We can't easily
      allocate memory here, so for now assume that we can save a

Since 64999 was written against Z there might be an additional change needed to
make that work.